MPG (US) to MPG (UK)
1 mile per gallon (US) equals 1.200949926 miles per gallon (imperial) (rounded).
How to convert miles per gallon (US) to miles per gallon (imperial)
To convert miles per gallon (US) to miles per gallon (imperial), multiply the number of miles per gallon (US) by 1.200949926. The factor is rounded to 10 significant digits. To go the other way, multiply miles per gallon (imperial) by 0.8326741846 (rounded).
miles per gallon (imperial) = miles per gallon (US) × 1.200949926
Example: 10 miles per gallon (US) = 12.00949926 miles per gallon (imperial).
Miles per gallon rises as a car gets more efficient, while liters per 100 km falls. The conversion between them is a reciprocal (for US mpg: L/100 km = 235.215 ÷ mpg).
About these units
Mile Per Gallon (US) (mpg (US))
Miles traveled on one US gallon of fuel. The standard fuel-economy unit in the United States; higher is better.
American fuel economy became a matter of policy in the 1970s. After the 1973 Arab oil embargo, Congress enacted the Corporate Average Fuel Economy rules in 1975, setting a sales-weighted average for each manufacturer's cars and light trucks. Fleet economy had been sliding until 1973, reaching a low of about 13.4 mpg, then rose as fuel costs rose: about 17 mpg in 1978, 22 in 1982, and about 25.4 mpg for the average new vehicle in the 2020 model year. Earlier still, the Mobil Economy Run (1936 to 1968) tested real-world mileage on a coast-to-coast route.
The US gallon is legally 231 cubic inches, or 3.785411784 litres. It descends from the English wine gallon, redefined as 231 cubic inches in 1706 under Queen Anne and adopted as the US standard in 1836. It is about 17 percent smaller than the imperial gallon, so US mpg figures look lower than British ones for the same car. Mpg has a quirk known as the MPG illusion: going from 10 to 20 mpg halves fuel use, but going from 50 to 60 mpg saves far less, even though both are 10 mpg gains. For that reason the EPA label also shows gallons per 100 miles.
1 mile per gallon (US) = 0.4251437074 kilometers per liter (approximately).
Sources: Wikipedia: Fuel economy in automobiles; Wikipedia: Imperial gallon; fueleconomy.gov: Learn more about the gasoline label
Mile Per Gallon (imperial) (mpg (UK))
Miles traveled on one imperial gallon (4.546 L). The UK still quotes fuel economy this way, so UK mpg figures are about 20% higher than US ones for the same car.
Britain's gallon is a child of the 1824 reform. It was originally defined as the volume of 10 pounds of distilled water at 62 degrees Fahrenheit, taken as 277.274 cubic inches; an 1889 Order in Council changed the figure to 277.463 cubic inches, and in 1976 the UK adopted the metric definition of exactly 4.54609 litres, after Canada had done so. The gallon used in the United States comes from a different, older wine measure, so the two differ by about 20 percent.
One imperial gallon is about 1.2 US gallons, which means that a car rated at 40 mpg in the UK delivers only about 33 mpg on the US scale. Miles per imperial gallon is still the UK's main fuel-economy unit even though petrol is sold by the litre and selling goods by the imperial gallon is no longer legal in Britain. Some Caribbean territories, such as the Cayman Islands and Grenada, still sell petrol by the imperial gallon, while the UAE, Guyana and Myanmar switched to litres in 2010, 2013 and 2014. When a figure says only mpg, check which gallon is meant.
1 mile per gallon (imperial) = 0.3540061899 kilometers per liter (approximately).
Sources: Wikipedia: Imperial gallon; Wikipedia: Fuel economy in automobiles
Related conversions
- MPG (UK) to MPG (US) (reverse)
- MPG (US) to km/L
- MPG (US) to L/100 km
- MPG (US) to mi/L
- MPG (US) to gal/100 mi (US)
- MPG (US) to gal/100 mi (UK)
- MPG (US) to L/mil
- Km/L to MPG (UK)
- L/100 km to MPG (UK)
- Mi/L to MPG (UK)
- Gal/100 mi (US) to MPG (UK)
- Gal/100 mi (UK) to MPG (UK)
- L/mil to MPG (UK)
See all fuel economy units.